Process for the extraction of mercury from mercury-bearing ores or products



V PRocEss roarnii nirnactfofu or ME URY FROM MERCURY-BEARING onus on v s a I Patented Oct; 20, 1931.

v sruenrcnonsnietn; 0 bENvER ooLonADo f I awnj rnonucrs Q Wms-i.

' invention relates to the. extraction of l'ner cury from mercury ores and products containing mercuryin'sulphide form, and it consists; briefly in leaching such ores and products with a suitable solvent or lixiviant, and recoyeringthemer'cury from the'lixivium thus obtained The solvent ordixiviant may b'e'regenerated 'at'the same time forthe treatment'ofnew material.

The inventionis based'on the fact that'certain metals; for example, the copper,- mercury silver "group; when 'in" a suitable solution medium are electro negative to the sulphide salts of the othermetals' of that group, hereas they become electro -'positiye in their action when in a metallic condition: 1 V

My process consists inleachingxoresor products containing" cinnabar and other qmer cury minerals with a double salt of SOdlUIIP' cuprous thiosulphate dissolved in} an excess of sodium thiosulphate, commonly 'known and sold on the market as sodium hyposulphite pnhy osulphite o'f-soda; In this. description I' shall use'the' chemical names of the saltsrather than the common orcommers cial names, although the saltjis'one and the same; 7 The double salti-of sodium-cuprous thiosulphate is not readily's'oluble in Water Weight of commercial ho per sulphate to form the desired solutionof the double salt of zsodium cuprous"thiosu'lphate in. Water.

have omitted'.-the, "Water of" crystallization from" the chemical formulae of the salts named. a 1'3NagSQH' S0; Nass souzsao euasoamash;

'"'j al rlicatib 'filea 11115 '9, 1929. "Serial mu'arzos; j

I Wish it'understoodthat Ido not confine myself to'. any definite Weightsofwsalts in' forming this solvent or lixiviant, but give the approximate Weights that will'form'work-f able solutions and'onlyconfine myself to thestatementthat there shall be sufficient V excess ofsodiumt-thiosulphate togkeep the double salt of lsodiurn-cuprou's thios ulphate in solution. As ar'rule,. the greater the excess of'sodium thiosulphate in solution the more stable-the solution of the-double salt becomes. and thereis'less danger ofldecompojsition and;

separation of:cuproussulphide; For-exam: ple, a solutloncontaining fourgand; one:halfparts by Weight ofcomm ercial sodium ,thio- .1 sulphate to one partby Weight of commercial; 9

coppersulphate is more stable'than: a, soluev ,tion containing theproportion of salts named 'a bove. v v .r I wish it understood also that I do,notjcon-- fine myself-to the use of sodium thiosulphate if the thiosulphatesof otheralkaline metals or alkaline earths shouldp'rove more econom- 1cal' or suitable forrleaching purposes; nor

do I confine myself to the formation and use ofcuprous-thiosulphate in making the double salt Withthe alkaline-metal or alkaline, r

earth thiosuhohate,v if other metals will perform similar electromotive reactions and :re- 7 generate the hxlviant." For the sake of clearness, however, Ifshall confine myself in this. description to the use of sodium thiosulphate and-'"the double salt of sodium-cuprous-thiofsulphate. llnoperatin'g my process, the ore or product is groun'dtolfa suitable fineness" thathwill liberate the mercury minerals and expose .7 Thechemical reaction is shownrbyithe-follow- "them to a free and qulck Teactlon' 'Wlth the ingfequationu Fort-he sake-of simplicity, I

solyent OrliXiViantL The finenessof com-r minution also depends on thefcharacter and condition of the mercury mineI' S,Whether- 1 V crystalline or amorphous The'comminuted tation, or by counter-current methods-, f ytith" by the 'cuprous thiosulphate and themercury passes into'solution While copper is precipitated as cuprous sulphide as indicated by the following simplified equation:

This equation is only illustrative, it. being apparent that the reactions are probably more complicated due ,to the formation of other double salts orth'e higher thionate's in" the presence oi an excess of sodium thiosul 7 phate.

To "the mercury in this solution, metallic copper becomes electro posit-iye and the mer cury may, therefore, be recovered irom solution'by passing the 'lixivium over metallic copperyw hich will precipitate metallic 11161 ege'nerate the lix' iviant according to'the'following-equation:

In order to iaci li ta te the recovery of the mercury, lprefertouse the substitution *meta l iiithe forni' of a voltaic couple, using suitable electrop'ositivemetal, such as co ppen 'tfor the anode, and a suitable electronegative ele- :ment, such mercury, :as a cathode. "This will generate 'suflicienit electromotiveifiorce t'o precipitate the mercury from solution on the cathode while the anode; if copper-v, p'asses r into sol utionancl regenerates the 'liiaiviaai t. I The. mercury may likewlse be recovered from the above named lixivium bynie'ans of.

a feeble electric current, with a density suff cien tlylo' vv so asnot to'destroy the lirnivium,

and using,pi-'efera'bly, copper for the anode ters aP-atent is:

and mer-"c'ury"for" t ll e cathode in' order to regenerate the liX-i'vium as stated above."

As an example of the above method of treatment, I have leached ore containing 92 pounds of mercury per ton with fa dilute solution of sodiuinthiosulphate containing s'odium cup -oas tllfl osulpliate l and, under Harte-commercial 'cpnclitions, have-extracted all but 056 pound or mercury "from the 1013. have taken the lix'iviurnYthnsobtained and have precipitated the mercury from solution by means or metallic copper, according to each of the methods above described, andh-ave recovered over 599% ofthe mercury from solution and rat the same time have reg enerated the l'lXlV'la'Il-tand returned it 'to the ore for renewed leaching and extraction.

7 fin ad-ifierent class of oreicofltaininggdi pounds of mercury per ton, have made an extraction of over 80% of the mercury from the me and a recovery :of over 99% of the mercury :from solution.

.What I claim and desire to secure-by Letl. A processfor extracting mercury from sulphide ores of mercury,consisting in leaching such ores With a solution consisting of a double salt of an alkaline-metal thiosulphate or alkaline-earth thiosulphate (commonly known and sold on the market as hyposulphite) and a metallic thiosulphate, dissolved in an excess of the alkaline-metal thiosulphate, or alkaline-earth thiosulphate.

2. A process. for extracting mercury from sulphide :ores 10f mercury,consisting in leaching such ores with a solution "consisting of a double salt of an alkaline-metal thiosulphate or alkaline earth V thiosulphate (commonly "known-and sol-don themarket as hyposulphite) andlametallic thiosulphate dissolved "1 in an excess or the alkaline metal' 'thiosul- 'p'hate, or alkaline-earththiosulphate, and recovering the mercury from suchlixivium,

3. A process for extracting mercury from 'sulphideores ofsmercury consisuirng in leachi'ng'suoh oresW-ith a solution consisting iofya double salt of an alkaline-metal thiosulphate or alkaline-earth thiosulphate: i-(comrmonly lmo-Wn and sold (011 themarket as hyposulwhite) and a metallic thiosulphate, dissolved in an excess of the :alkalineemetal thiosulphate, o'r 'a'l'lealine -earth thiosulphate, and re covering the mercury fromdsuch lixivium, by the substitution of a metal that twillprecipimm the mercury in a .met-alliocondition and atit'he same time regeneraterzthe lixivia-nt gto its liormer rpotencyn 7 i4. process foriextraicting mercury-from sulphide acres of mercury; consisting in Is ach ing such ores with :asol u-tion consisting'of a double salt or an alkaline-metal thiosulphate or alkaline-earth thiiosulphate (commonl y known and sold on the market as .hyposul: white.) and :a metallic thiosulphate;@dissolved in can excess of the zal'kaline metalthiosulphat-e or alkaline-earth thiosulphate, and recovering the mercury from suoh lixivium by meansof a ivoltaiccouple in Whiohfanelectrd negative element is Su-sed for theicathode and a more electropositivel metal is used ,for the anode, which at the same time will regeneritheilixiwiant to its former potency.

' A processiorllextrac'ting mercury from sulphide-ores of mercury, consisting in leachape in such 'OBQS with a solution consisting of a ou'ble salt of an alkalinemetal thiosulphate alkaline-earth thiosulphate (commonly and sold on the market as h-yaposulwhite) and .a: metallic thiosulphate, "dissolved an exce'ss 0f; the alkaline-metal thiosulqohat'e or alkaline-earth thiosulphate, and rea covering the mercuryjfromisuch liaxiiviumby means of electrolysis.

' -6. A process 01" extracting mercury from sulpl'ri-de orescf mercury, conslstingsiai leach angsuc'h ores a solution G0IlS1S'tlIl'gof a double salt of an alkaline-metal thiosulphate or alkaline-earth ihiiosul'phate'commonla es-Wis s oldc r hqr e 'lse yp s phite) and a metallic thiosulphate{dissolved in an excess of the alkaline-metal thiosul- 1 phate, or alkaline-earth thiosulphate,and recovering the mercury from such lixivium by means of electrolysis in a cell having an;electronegative element for the cathode and having a metal for the anode, that Will regenerate the lixiviant to its former potency.

7. Aprocess'for'extractingmercury from sulphide ores of mercury,consisting in leach ing such ores 'With a double-salt of an alkaline-metal thiosulphate and cuprous thiosul-c, v phate, dissolved in an excess ofthe alkaline v I netal thiosulphate.-

8. A process forextracting mercury from sulphide ores of mercury, consisting in leaching such ores with a d0uble saltof sodiurncuprous thiosulphate dissolved in of sodiurn'thiosulphate.

In testimony whereof 'I signature. v

STUART CROASDALE.

an excess have aflixed my 7 

